A study of more than 35,000 subjects has found that people who drink sugary soft drinks have an increased risk of developing several obesity-related cancers, even if the person is not overweight. The study rekindles the controversial debate over whether excessive sugar consumption directly contributes to cancer.

The new associational study came from joint research between the University of Melbourne and the Cancer Council of Victoria. The data was gathered from 35,593 participants reporting 3,283 obesity-related cancers, including kidney, colorectum, oesophagus, pancreas, liver, and gallbladder.

The study found a strong correlation between the consumption of sugary soft drinks and the development of 11 cancer types. Most strikingly, this correlation between cancer risk and soft drink consumption was found regardless of the size and weight of the participants.

"We were surprised to find this increased cancer risk is not driven completely by obesity," says Alison Hodge, one of the researchers on the project. "Even people who are not overweight have an increased cancer risk if they regularly drink sugary soft drinks."

The study also found that the increased cancer risk was only present in those subjects that drank regular sugary soft drinks and not those that consumed "diet" soft drinks with artificial sweeteners. The implication here is that sugar is the primary culprit in the raised cancer risk.

While sugar is definitely strongly connected to both obesity and diabetes, its direct role in cancer has been hotly debated. A controversial study last year revealed a disturbing mechanism that illustrated how sugar stimulates cancer cells and possibly accelerates tumor growth. The study was undeniably unsettling, but also unclear in determining how broadly it could be applied to straightforward human sugar consumption. After all, sugar does fundamentally feed all the cells in our body and it's pretty vital to any healthy human being.

Over the last few decades, there have consistently been a variety of small studies published that link sugar consumption to an increased incidence of certain cancers, from breast to colorectal, but these associations have never been clearly clinically validated. In fact, larger studies have consistently found no major association between cancer and increased sugar consumption.

Generally, the link between sugar and cancer is sandwiched around obesity. Sugar leads to obesity and obesity certainly carries with it an increased risk of cancer. But this latest study delivers a strange anomalous chunk of data into the mix by finding an increased risk of cancer linked to sugary drink consumption that is unrelated to a subject's weight.

All this ultimately leaves us in a "we don't really know" situation regarding a direct connection between sugar consumption and cancer. Certainly depriving the human body of all sugar is not the solution as glucose is fundamental to powering the cells in our body, but there assuredly is no harm in cutting down the volume of added and refined sugar we consume, either in soft drinks or otherwise.

The new study was published in the journal Public Health Nutrition.